The present invention relates generally to optical switches, and in particular fiber optic wavelength switching with multiple tunable optical ports.
The growth of the Internet and other broadband services demands increased capacity of long haul and metropolitan communication infrastructures. The increased bandwidth provided by fiber optic systems is often insufficient to support such demand, and fiber exhaustion is now a concern for many network operators. In the past, a practical alternative that satisfied demand for more bandwidth at established bit rates is dense wavelength division multiplexing (DWDM), which combines many wavelengths of light at a variety of bit rates onto a signal optical fiber. However, as more transmission bandwidth becomes equivalent to more optical wavelengths, the saturated capacity and economic viability of electronic digital cross-connects (DXCs), add/drop multiplexers (ADMs), and fault management architectures can become problematic. Motivation is increasing to manage bandwidth optically rather than electronically.
Current devices used to move in the optical management direction include optical add/drop multiplexers (OADMs) and configurable OADMs (COADMs). OADMs provide fixed access to a subset of wavelengths in a DWDM system and provide static bandwidth management. OADMs have no routing flexibility and generally have no provision for monitoring signal power. COADMs expand OADMs because of dynamic configurability.
For example, an input fiber may have 40 wavelengths with 100 GHz ITU grid spacing. A demultiplexer (DEMUX) separates a subset of the wavelengths and sends each subset to 2xc3x972 optical switches (for example) that either pass through or drop signals and allow the addition of a particular wavelength. All wavelengths are then combined by a multiplexer (MUX) onto the output fiber. The systems may include attenuators on the drop or through channels to equalize optical power, and there can be optical power tabs and photodiodes to monitor signal power or status of each wavelength.
Another traditional solution involves full wavelength cross-connect capable switching any wavelength from any incoming port to any outgoing port. However, full cross-connect switches are typically complex due to large beam steering requirements.
Consequently, there is a need for an optical switch that enhances the functionality and effectiveness of a COADM based system without the complexities associated with full cross-connect switches.
In accordance with one aspect of the present invention there is provided a fiber optic wavelength switch comprising: (a) a front-end unit having a plurality of optical ports, said front-end unit comprising: (i) a fiber array comprising a plurality of fibers coupled to the plurality of optical ports for transmitting and receiving optical signals; (ii) a micro-lens array having a plurality of micro-lenses, each micro-lens being coupled to a respective fiber; and (iii) a lens for receiving and re-directing the optical signals from the micro-lens array; (b) a wavelength dispersion element defining a dispersion plane; (c) a light redirecting element associated with the wavelength dispersion element; and (d) an actuation array operative with the light redirecting element for tilting the optical signals substantially perpendicular to the dispersion plane defined by the wavelength dispersion element.
In accordance with another aspect of the present invention there is provided an optical device for rerouting and modifying an optical signal comprising: (a) a front-end unit having a first port for launching a beam of light and a second port for receiving a beam of light, said front-end unit comprising: (i) a fiber array comprising a plurality of fibers coupled to the first port for transmitting beams of light and to the second port for receiving beams of light; (ii) a micro-lens array having a plurality of micro-lenses, each micro-lens being coupled to a respective fiber; and (iii) a lens for receiving and re-directing the beams of light from the micro-lens array; (b) a light redirecting element having a focal plane for receiving the beam of light launched from the first port; (c) a wavelength dispersion element defining a dispersion plane and disposed substantially at the focal plane of the light redirecting element for spatially dispersing a reflected beam of light from the light redirecting element and for redirecting the spatially dispersed beam of light back to the light redirecting element; and (d) an actuation array disposed at the focal plane of the light redirecting element for modifying the spatially dispersed beam of light reflected from the light redirecting element in a direction substantially perpendicular to the dispersion plane defined by the wavelength dispersion element and for reflecting the modified spatially dispersed beam back to the second port of the front-end unit through the light redirecting element and the wavelength dispersion element.
In accordance with another aspect of the present invention there is provided a method of rerouting and modifying an optical signal comprising: (a) launching a beam of light towards a reflecting element having a focal plane; (b) redirecting the beam of light incident on the reflecting element to a dispersion element defining a dispersion direction, said dispersion element disposed substantially at the focal plane; (c) spatially dispersing the redirected beam of light into a plurality of different sub-beams of light corresponding to a plurality of different spectral channels; (d) redirecting the plurality of different sub-beams of light to an actuation array optically disposed substantially at the focal plane; (e) selectively modifying the plurality of different sub-beams of light in a direction substantially perpendicular to the dispersion direction and reflecting them in a substantially backwards direction; and (f) redirecting the selectively modified plurality of different sub-beams to the dispersion element and combining them to form output beams of light.
In accordance with another aspect of the present invention there is provided an optical device for rerouting and modifying an optical signal comprising: (a) a first port for launching a beam of light, said first port comprising: (i) a fiber coupled to the first port for transmitting and receiving optical signals; (ii) a micro-lens coupled to the fiber; and (iii) a lens for receiving and re-directing the optical signals from the micro-lens; (b) a first light re-directing element having a focal plane for receiving the beam of light launched from the first port; (c) a first wavelength dispersion element defining a dispersion direction and disposed substantially at the focal plane of the light redirecting element for spatially dispersing a reflected beam of light from the light redirecting element and for redirecting the spatially dispersed beam of light back to the light redirecting element; (d) a transmissive deflector disposed substantially at the focal plane for receiving the spatially dispersed beam of light reflected from the first light redirecting element and redirecting the spatially dispersed beam of light in a direction substantially perpendicular to the dispersion direction defined by the first wavelength dispersion element; (e) a second light redirecting element for receiving the spatially dispersed beam of light from the transmissive deflector; and (f) a second wavelength dispersion element for recombining the spatially dispersed beam of light from the second light redirecting element and for directing the recombined beam of light to the second light redirecting element.
In accordance with another aspect of the present invention there is provided a fiber optic wavelength switch comprising: (a) a front-end unit having a plurality of optical ports coupled to a plurality of lenses for transmitting and receiving beams of light; (b) a wavelength dispersion element defining a dispersion direction; (c) a light redirecting element associated with the wavelength dispersion element; and (d) an actuation array operative with the light redirecting element for tilting the beams of light substantially perpendicular to the dispersion direction defined by the wavelength dispersion element.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.